Except customer service is often trying to help you remember, and you can guess a few times.... a scammer will say something like, "Oh man, I can't remember what I picked... sometimes I choose a random car model, but sometimes I just put random characters", and if either is true, the customer service rep might confirm it.

Incidentally, I've also had customer service go the other way. I was doing a security check, and one of the questions was how long have you lived at your current address. We moved when I was about 10, so I said "I think it's XX years, let me double check: Mum, how long have we lived here, is it XX or XX+1 years?", only to get "It has to be YOUR answers". Despite knowing all the other relevant answers (random characters of password, memorable name and date, amount of last Direct Debit, down to the pence, first line of address and post code) first time and without prompting, it ended up with my account being locked.

Definitely more security, but _maybe_ slightly too far in the other direction.